I've seen these all over the blogosphere and have wanted to try them for literally years--Hi Hat cupcakes. I'm not sure where the name really comes from but the concept is simple...cupcakes with chocolate dipped frosting.
I started with chocolate cupcakes and peanut butter frosting (as far as I'm concerned you can never go wrong with that combination). The general idea is that you swirl the frosting high on top of the cupcake--at least that's how I've seen them in the past--then put them in the freezer for a while to firm up before dipping them in melted chocolate.
I think my frosting turned out to be more like regular height...something to keep in mind for the next time. Once they were all frosted, I put them in the freezer while I got the chocolate coating ready.
I poured a bag of milk chocolate chips in a glass pyrex measuring cup and heated it in the microwave for 20 seconds at a time, stirring in between, until they were completely melted. I added a couple of tablespoons of peanut oil (I'm not sure it has to be peanut oil, but I had a little note from some recipe I found forever ago that said peanut oil...so that's what I used) and stirred it in. I dipped the frosting portion of the semi-frozen cupcakes in the chocolate sauce and set them up to cool--easy. Messy, but easy.
The only downside to these is that you have to store them in the fridge. If they are left out at room temperature, the chocolate doesn't hold up too well.